What tool is used to measure the inside, outside, and depth of a hole?

The tool specifically designed for measuring the inside, outside, and depth of a hole is the vernier caliper. This instrument features two sets of jaws: one for measuring external dimensions and the other for internal dimensions. Additionally, it has a depth rod that extends from the bottom of the jaws to measure depth accurately.

While micrometers are often used for precise measurements, they typically focus on external measurements and are not as versatile as vernier calipers for different types of measurements like depth or internal diameters. Feeler gauges are primarily used to measure gaps or clearances between parts, and they're not suited for measuring the dimensions of holes directly. A digital caliper can also measure internal, external, and depth dimensions, and although it provides ease of reading with a digital display, the vernier caliper is still widely recognized for its versatility and accuracy, especially in various engineering applications.