Hueco. I think that most of the dial calipers you will find only go to .001. You should be able to estimate to .0005 without any problem. I'm a retired weatherman, and one of the tasks I had was what was called a barometer comparison. This is where you compare the station's aneroid baromter with a mercurial barometer. We had to read them to the nearest .0001 inch of mercury for the comparison. I am able to read my Mitutoyo dial caliper pretty close to .0001 because of that experience. I doubt that I am ever too far off. Of course, 33 years of practice has something to do with that.
I would imagine that if you went to a supply house that catered to the machinist trade, you could find a dial caliper that read to .0001, but my guess is that it would be very expensive. Won't hurt you to look though.