In metrology, the micrometer is not able to do depht measures with no association with other devices. The same millimeter thread, and other components, can be used to this goal. It just need some modifications. In the offices the inside micrometer is also known as imicro.
You must be familiarized with the use of the external micrometer. The reading of the inside micrometer follows the same logic. However, it's necessary, to take some cautions. Interact with the simulator below and see that the line coined the sleeve correspond to the millimeter covered by the thimble. Other detail, is that the increment of hundredths is done in the opposite direction to the obseverved in the micrometer.
The model of the inside micrometer used on this simulator is has an open interpretation. There are some presentations (types) of these instruments. Micrometer like caliper, inside micrometer of three contacts and tubular inside micrometer are some examples. However, all have in commoen the same method for reading and interpretation.