With the recent thriving of low-power electronic microdevices and sensors the development of components capable of scavenging environmental energy has become imperative. In this work we studied bidomain congruent LiNbO3 (LN) single crystals combined with magnetic materials for dual, mechanical and magnetic, energy harvesting applications. A simple magnetomechano- electric composite cantilever, with a tri-layered long-bar bidomain LN / spring-steel / metglas structure and a large tip proof permanent magnet, was fabricated. Its vibration and magnetic energy harvesting capabilities were tested while trying to optimize its resonant characteristics, load impedance and tip proof mass. The vibration measurements yielded a peak open-circuit voltage of 2.42 kV/g, short-circuit current of 60.1 μA/g and average power of up to 35.6 mW/g2, corresponding to a power density of 6.9 mW/(cm3·g2), at a low resonance frequency of 29.22 Hz and with an optimal load of 40 MΩ. The magnetic response revealed a resonant peak open-circuit voltage of 90.9 V/Oe and an average power of up to 49.9 μW/Oe2, corresponding to a relatively large magnetoelectric coefficient of 1.82 kV/(cm·Oe) and power density of 9.7 μW/(cm3·Oe2). We thus developed a system that is, in principle, able to scavenge electrical power simultaneously from low-level ambient mechanical and magnetic sources to feed low-power electronic devices.