  We demonstrate a versatile variable field module (VFM) with capability of
both field and angular dependent measurements up to 1800 Oe for scanning probe
system. The magnetic field strength is changed by adjusting the distance
between a rare earth magnet and the probe tip and is monitored in-situ by a
built-in Hall sensor. Rotating the magnet allows the field vector to change
from the horizontal to vertical direction and makes it possible to do angular
dependent measurements. The capability of the VFM system is demonstrated by
degaussing a floppy disk media with increasing magnetic field. Angular
dependent measurements clearly show the evolution of magnetic domain
structures, with a completely reversible magnetic force microscopy phase
contrast observed when the magnetic field is rotated by 180{\deg}. A further
demonstration of out-of-plane and in-plane magnetic switching of CoFe2O4
pillars in CoFe2O4-BiFeO3 nanocomposites was presented and discussed.
