How do you read a micrometer to get a measurement of 4.72 mm?

The main scale shows markings in millimeters (above the line) and half-millimeters (below the line). The edge of the thimble has passed the $4 \text{ mm}$ mark and also the $0.5 \text{ mm}$ mark after the $4 \text{ mm}$ mark.

$$\text{Main scale reading} = 4.5 \text{ mm}$$

The thimble scale has divisions, where each division represents $0.01 \text{ mm}$. The line on the thimble that aligns with the main line on the sleeve is the $22^{\text{nd}}$ division.

$$\text{Thimble scale reading} = 22 \times 0.01 \text{ mm} = 0.22 \text{ mm}$$

Add the main scale reading and the thimble scale reading.

$$\text{Total measurement} = \text{Main scale reading} + \text{Thimble scale reading}$$ $$\text{Total measurement} = 4.5 \text{ mm} + 0.22 \text{ mm} = 4.72 \text{ mm}$$

The measurement shown on the micrometer is $\text{4.72 mm}$.