OK, but what makes the cantilever move across the sample? You might think it is movement of the stage on which the sample sits. In fact that motor driven motion is much too crude.
Instead the SPM again uses the piezoelectric tube:
If a voltage is applied to the upper right electrode, that side of the tube shrinks slightly causing the tube to bend a little bit to the right. Voltage on the left electrode then bends the tube (and the cantilever) to the left. Remember that the actual piezo is ~ 100 times larger so very small bends are adequate.
