Yes, dial calipers can be disassembled, although the dial mechanism may not be the problem.. instead, there could be dirt/debris in the rack and pinion gear located behind the dial mechanism/gear box.
Another part to check would be the slide lock, which holds the slide properly aligned on the bar. Some have tiny setscrews that can be adjusted to eliminate any slop in the fitting of the slide. Errors are introduced when/if the jaws aren't nearly perfectly parallel.
With the caliper in the full open position, some solvent and a small brush can be used to clean the exposed rack (a good magnifier lamp is helpful), and with a little fiddling, a drop of solvent can be applied to the small pinion gear that meshes with the rack. Some duster/canned propellant can be used to blow out excess solvent and likely, the dirt with it.
Opening the actual dial mechanism may be fairly easy, or possibly somewhat difficult if one isn't familiar with small mechanisms. A puller may be needed for pulling the pointer off, but maybe not.. they can often be persuaded to come off with some gentle manipulation.
Under the dial face is where the small gears are, and a tensioning spring to eliminate backlash. It's less likely that dirt or foreign objects have entered the gear case, but maybe something has gotten in there. It's best if the slide stays slightly tensioned, so the back pinion gear doesn't skip and need resetting, which can be a little troublesome if required.