5 cm is really small, it's not enough..
what resolution do you need?
You could use one sensor and move it up/down with very little steps and search for the maximum signal.
you get values e.g. like
1 1 1 1 2 2 2 33 55 55 55 40 5 2 1 1 1
Then you can calculate that the max signal is probably a bit right of the middle 55.