Yes
Millimeters.
You would use mm. For the same reason you use feet instead of miles to measure the height of a building.
Thickness is measured in units of length. You'd have to choose the one that gives a reasonable number corresponding to whatever you're measuring the thickness of. If it's the thickness of a hair, you'd probably select a sub-multiple of a meter. If it's the thickness of the atmosphere, you might select the kilometer. If it's the thickness of country gravy, that's a whole different story.
Milimeter
Millimeters.
Millimetres, as in 1.5 mm. You could use a micrometer to measure thickness of a coin.
You could describe that measurement accurately and precisely with any unit of length.But the 'millimeter' would probably produce the most convenient number.
With a micrometer (caliper) To measure the thinkness you use mm's
Millimeters.
You would use mm. For the same reason you use feet instead of miles to measure the height of a building.
Coins are measured in millimetres.
Typically you might use "mm" for coins. For currency, I would suggest micron units.The millimeter.
Millimeter
It depends upon the size of the object to be measured . for small beads , thickness of a page and nails of finger can be calculated in mm .An instrument called screw gauge is used for the same.
The best way to measure thickness is to use an ultrasonic transducer. You use the back reflection to figure out the thickness.
volume
What measure of units would you use to measure the thickness of a phone book