Inductive Loop Sensor

I'm not familiar with inductor. I need this metal sensor for my project. Unfortunately all info I got from the internet are all about the whole device, which is connected to the buzzer.

Any one here has any idea or schematic on how to create inductive loop sensor that can output an analog signal or just high/low signal to micro-controller?

 

is there any more simple ones? I will be using it for car park system for arrival of car until it leaves the sensor.