Could you be more specific?

You will have to apply a force on the cantilever to move it. If using electrostatics for actuation, you could apply a voltage and then run the simulation. P.S. if you are not using a MEMS module, you will have to use ALE and also couple the electrostatics and structural modules.

In case, you have simulated and want to see the deflection as results, you can find that easily in the results tab. Search for tutorials for analyzing the results

The deflection along the length of a cantilever depends on the applied force (point force, distributed force,...) and where it is applied (center of the beam, near the anchor, at the free-end,...). There are analytic expressions for all cases you can find in the literature.

If you are trying to run a FEM simulation, I advice you to go carefully through the tutorials and examples in the comsol website.