inductive proximity sensors

Inductive proximity sensors are noncontact proximity devices that set up a radio frequency field with an oscillator and a coil. The presence of an object in front of the sensor changes this RF field and the sensor is able to detect the presence of an object.

An inductive proximity sensor comprises an LC oscillating circuit, a signal evaluator, and a switching amplifier. The coil generates a high-frequency electromagnetic alternating field. This field is emitted at the sensing face of the sensor. If a metallic object (acts as a trigger) nears the sensing face, eddy currents are generated. The resultant losses of energy are drawn from the oscillating circuit and reduce the oscillations. The signal evaluator circuit in the LC oscillating circuit converts this information into a clear signal.

The measurement of proximity, position and displacement of objects is essential in many different applications such as valve position, level detection, process control, machine control

Can these sensors output distances directly or do they just act as switches?

If I want to output distance, what would be a suitable sensor?