Which of the following devices is least likely to be used for precise hole measurements?

The device identified as the least likely to be used for precise hole measurements is the protractor. Protractors are primarily designed for measuring angles rather than linear dimensions or hole sizes. They are more suitable for applications where angle measurement is required, such as in geometry or layout work.

In contrast, dial indicators, calipers, and micrometers are all precision measuring instruments tailored for accurately assessing linear dimensions, including hole sizes. Dial indicators can provide precise measurements and feedback for depth and displacement, calipers offer versatility in measuring internal and external dimensions as well as depths, and micrometers are specifically calibrated for high accuracy in measuring small distances. Therefore, among the options, the protractor's primary function does not align with the requirements for precise hole measurements, making it the least relevant tool in this context.