Hello, to check a inductif sensor(suposed 2wires) you have a magnet with a coilaround just like an relay switch, so you should be able to mesure the resistance over the coil.... can be from 50 ohms to roughly 500/750 ohms. if you move a little metal in front of it the ohmmetre should vary in reading, equal to the mouvement.
then you have inductive active sensors 3wires. this means you have still your coil around a non magnetic ferous metal, so you could again mesure the ohm's, and the third wire, is an 12 volts one who wile energised will make the metal magnetic(same as the function of a relay, 3wires 1)12v 2) earth 3) signal(same line as the 12volts entree.
the other category are hall effect sensors who have again 3 wires +12v earth signal, and here you only can detect signal by means of open up (in serie) the signal line and to mesure in millamps the strengt and in parrallel the outcomming voltage . the latest ones - hall sensors are two wire ones actif where only the drop in voltage is mesured