  Quantum phenomena at interfaces create functionalities at the level of
materials. Ferromagnetism in van der Waals systems with diverse arrangements of
spins opened a pathway for utilizing proximity magnetic fields to activate
properties of materials which would otherwise require external stimuli.
Herewith, we realize this notion via creating heterostructures comprising bulk
CrCl$_3$ ferromagnet with in-plane easy-axis magnetization and monolayer
WSe$_2$ semiconductor. We demonstrate that the in-plane component of the
proximity field activates the dark excitons within WSe$_2$. Zero-external-field
emission from the dark states allowed us to establish the in-plane and
out-of-plane components of the proximity field via inspection of the emission
intensity and Zeeman effect, yielding canted orientations at the degree range
of $10^{\circ}$ $-$ $30^{\circ}$ at different locations of the
heterostructures, attributed to the features of interfacial topography. Our
findings are relevant for the development of spintronics and valleytronics with
long-lived dark states in technological timescales and sensing applications of
local magnetic fields realized simultaneously in multiple dimensions.
