  Quantum sensing exploits the strong sensitivity of quantum systems to measure
small external signals. The nitrogen-vacancy (NV) center in diamond is one of
the most promising platforms for real-world quantum sensing applications,
predominantly used as a magnetometer. However, its magnetic field sensitivity
vanishes when a bias magnetic field acts perpendicular to the NV axis. Here, we
introduce a novel sensing strategy assisted by the nitrogen nuclear spin that
uses the entanglement between the electron and nuclear spins to restore the
magnetic field sensitivity. This, in turn, allows us to detect small changes in
the magnetic field angle relative to the NV axis. Furthermore, based on the
same underlying principle, we show that the NV coupling strength to magnetic
noise, and hence its coherence time, exhibits a strong asymmetric angle
dependence. This allows us to uncover the directional properties of the local
magnetic environment and to realize maximal decoupling from anisotropic noise.
