TBH, if all you are doing is copying one control value, just to put in the clipboad to paste elsewhere, Ctrl+C is as quick as anything I would have thought. I'm all for making things more efficient, but even I would use Ctrl+C, rathers than locate a button and press it.
Now, I have used a button in the past, but that was to copy a control value and paste it into another Access DB that we had to use to keep track of the cases we worked, so I completed most of the data in that other DB and the user just had to confirm.?