For the calipers just check a 123 block. If they read within a half thou on all 3 dimensions they are likely just fine.
The mic is fussier. You should check it on a micrometer standard if you can. If you have access to some gage blocks, I would check it at .01000, .5000 and 1.0000. That will show that it is reading correct at various points on the range.
What are you looking to trade for? I'd be interested in the mic, particularly, but both for the right deal.