What do you mean by simulate?? Solve for values, produce a waveform??
If you are trying to solve for values, you can use a formula node to work it out for you and have the user input known values.
You can make it pretty "fancy" with an animation like you are pressing a button, etc. if you are trying to make it simulate in that sense (obviuoulsy this will take some time to create an aniumation). You could make while loop and using the known values for a sensor, have the "magnet" move closer and further from the sensor and create a waveform showing the field strength or switching of the sensor.
Let me know.
Kenny