  We develop a microscopic theory of tunneling spin transport at the magnetic
interface between a ferromagnetic insulator and a ferromagnetic superconductor
(FSC) driven by ferromagnetic resonance. We show that the spin susceptibilities
of the FSC can be extracted from the spin currents by tuning the easy axis of
the FSC, and thus the spin currents can be a probe for the symmetries of the
spin-triplet Cooper pairing. Our results will offer a route to exploiting the
synergy of magnetism and superconductivities for spin devices.
