Hall effect sensors

in hall effect sensors, the idea is that three elements are involved. the current, the magnetic field (Flux) and the voltage.

my question is that in proximity sensors, which are used in detecting magnetic materials, is any current source used?

Is the sensor considered as an active type sensor?

No, not just a plain current source.

It could be an oscillating circuit where frequenzy is tetermined by the sencors coil.