You can use a resistance meter to measure the resistance of the sensor as it is just a coil of wire.

Expect a reading between 800 and 1800 ohms.

You can then switch the meter to AC voltage and crank the engine.
You should see a voltage of at least 20 volts when disconnected from the ecu.

The only reliable way of checking its operation is when it is connected to the ecu and using an oscilloscope to view the wave form.