An ammeter and a voltmeter should be linked in order to verify Ohm's law:

The potential difference across a current-carrying wire is precisely proportional to the current flowing through it at a constant temperature, according to Ohm's law.

i.e.  V= IR

Here V= potential difference, R = resistance and I = current.

An ammeter is a device that measures the amount of electricity flowing through a circuit.

It has a very low resistance, ideally none at all.

When an ammeter is connected in series, it enables all of the circuit currents to currents through it, allowing it to be measured.

A voltmeter is a device that measures the voltage difference between two terminals in a circuit.

In a perfect world, a voltmeter would have infinite resistance.

When a voltmeter is connected in parallel with an infinite resistance, no current passes through the voltmeter and the voltage drop (IR) remains constant.

As a result, the ammeter should be linked in series and the voltmeter should be connected in parallel.