Cybernetics is a multi-disciplinary field that provides hope for those who have lost the ability to move their bodies. It is also a field that is rife with ethical dilemmas and grandiose promises. In a BBC article, Martin Angler explores the question of neural enhancement through cybernetic interfaces. The reality is that we have things like cochlear implants that convey signals to the brain. The dream is to implants to make people smarter and, perhaps, eventually full man/machine integration (a cyborg).
On a practical level, cybernetics teaches us about the difficulties in repairing lost function versus the difficulties of creating entirely new (and improved) functionality. This is a key distinction from an evolutionary perspective because one of the roles of natural selection (coupled with random mutations) in a Darwinian paradigm is to not only restore lost function or optimize current function, but also to create entirely new function.
Angler comments:

The dream is to create the type of brain augmentations we see in fiction that provide cyborgs with advantages or superhuman powers. But the ones being made in the lab only aim to restore lost functionality — whether it’s brain implants that restore limb control, or cochlear implants for hearing… Creating implants that improve cognitive capabilities, such as an enhanced vision “gadget” that can be taken from a shelf and plugged into our brain, or implants that can restore or enhance brain function is understandably a much tougher task. But some research groups are [beginning] to make some inroads.

Working within the design of a fully functioning organism is one thing. The difficult task of coming up with a design that will perform a function, then integrating it into the body, has already been accomplished for you. The components are there for a reason and as we have seen with genetics and neuroscience, these functions are intricately interwoven into the organism’s system. When a part of the body malfunctions, we still understand what it was meant to do. A broken foot is still a foot. In cybernetics, the goal is often to re-gain (or gain for the first time) functionality that should have been there in the first place. The components and structure are in place; there is either something missing, or something is malfunctioning.
If engineers struggle with adding new design components to the body, can we expect natural selection to do better? Natural selection coupled with mutations (and subsequent reproduction) can optimize an organism for its environment. Those organisms with traits that are best suited for a particular environment are able to live and reproduce, as in the case of bacterial resistance. If an organism lacks functionality that it should have, and this lack affects its ability to survive, then natural selection is optimizing the population for proper functionality, or at least it does so up to a point. This is limited to factors that affect survival.
However, this is not the same thing as producing a completely novel feature. Michael Behe addresses this in his book The Edge of Evolution. Natural selection acting on mutations can do things like adapt to environmental pressures, but the extent to which the organism changes is limited. Much as in cybernetics, to make a completely novel component would require an incredible amount of planning to overcome the barriers in integrating the component into a system. It isn’t just an matter of attaching a new piece, but of rewiring. Similarly, regarding claims that the Darwinian mechanisms can form novel components, it needs to be show how these mechanisms were also able to integrate the components into the already existing system so that the organism has some sort of survival advantage at each step of the process; otherwise there is no reason to expect the new components to be preserved into the next generation.
Cybernetics has helped restore hearing and movement to those who have lost them. It is a field that helps us understand the incredible biological and mechanical barriers that must be overcome in order to restore function. It also helps us understand what is entailed in adding novel functionality to an organism — it is about more than constructing a part, it also involves integrating that part into the body plan. It seems to entail quite a bit of goal-oriented planning and design. These are not strengths of Darwinian evolution.