If you want to enter an exact value in cm or mm to move while in meters, you need to enter Advanced Mode.

For example, to move 62 cm in X, type G (to move), X (constrain to x), = (or NumpadAsterix) to enter Advanced mode, then 62, and finally cm for centimeters. This process is a little convoluted though. It would be nice to be able to type cm or mm at any time without the advanced mode step as it is easy to get the steps out of order. I don’t know if anyone knows of a way to activate advanced mode at all times…

Supposedly you can hit Ctrl = or Ctrl NumpadAsterix to exit Advanced mode, but it will also return there automatically once you confirm the move with Enter. 🙂

Overall, it seems to be easier to just hold Shift (and zoom in) while moving things with unit snapping turned on than trying to fiddle with Advanced Mode, but it’s there if you need it.