I looted a cybernetic pain inhibitor and cybernetic limb actuator off of Kellogg's body and they are worth quite a bit of caps. I can't tell, however, if they're useful for anything else... like, are they something you can give to Valentine, for instance? Or are they just sellable junk pieces?
Pretty sure the post indicating you can have the implants installed by the Institute is a hoax.
I have completed the institute endgame (and non-radiant side quests) and talked to every named NPC in every division (nobody was killed or exiled), none of them mentions the implants when they are in my inventory and no doctors have this as an option in any sub menus.
Additional support of Grigoriprime's answer and further verification that the answer by Aaron is a hoax:
I have spoken to every individual in the institute I can find, none have made any reference to the implants. I did this both when I first entered, mid-way through the last act, and again after I finished the game siding with the institute.
At this point, there's no reason to believe these are anything but vendor trash. That being said, "needing" caps isn't something anyone that's this far in the story should be thinking. Might as well hold onto them, you never know.
Yes you can indeed use the Cybernetics as implants if you stuck qith the institute. If you have the limb actuator, you won't take any fall damage, and if you have the Pain inhibitor, you take 20% less damage from all enemies. If you talk to a doctor from the bio section after you side with the institute, he'll offer to inplant them