Mechanical systems are sensitive to a wide variety of extremely small forces, such as magnetic, optical, and gravitational. This sensitivity can enable coupling of mechanical resonators to individual quantum systems. In this work we use a single nitrogen vacancy (NV) center in diamond to detect the motion of a magnetized mechanical resonator at the picometer scale1. Utilizing the NV’s room temperature quantum coherence properties, we demonstrate coherent control of its spin state to detect both driven and Brownian motion of the resonator. The diamond NV center is a particularly promising spin qubit for applications in quantum information and ultrasensitive magnetometry, and furthermore, coupling NV centers to mechanical resonators provides a platform for integrating them into a hybrid quantum system. I also present ongoing work on high quality single crystal diamond mechanical resonators as a novel approach to ultrasensitive force detection and spin-phonon coupling.