which piece of equipment would you use to measure the current in a circuit?

The piece of equipment used to measure the current in a circuit is an ammeter.

In a typical school‑level or basics question like “which piece of equipment would you use to measure the current in a circuit?”, the expected one‑word answer is:

Ammeter

(If the context is more practical, a digital multimeter set to the current range can also be used, but the standard answer is “ammeter.”)