This paper presents the design, fabrication and preliminary characterization of highly sensitive MEMS-based Xylophone Bar Magnetometers (XBMs) realized in imec's poly-SiGe MEMS technology. Key for our Lorentz force driven capacitively sensed resonant sensor are the combination of reasonably high Q-factor and conductivity of imec's poly-SiGe, our optimized multiphysics sensor design targeting the maximization of the Q-factor in a wide temperature range as well as our proprietary monolithic above-CMOS integration and packaging schemes. Prototypes 3-axis devices were fabricated and characterized. We present optical vibrometer and electrical S-parameter measurements of XBMs performed in vacuum with a reference magnet at increasing sensor separation. The optical oscillation amplitude is well correlated with the magnetic field amplitude. The electrical 2-port measurements, 1st port as Lorentz force actuator and 2nd port as capacitive sensor, also reproduces the designed magnetic field dependence. This opens the way towards the on-chip integration of small footprint extremely sensitive magnetometers.