  Magnetic impurities inserted in a $s$-wave superconductor give rise to
spin-polarized in-gap states called Shiba states. We study the back-action of
these induced states on the dynamics of the classical moments. We show that the
Shiba state pertains to both reactive and dissipative torques acting on the
precessing classical spin that can be detected through ferromagnetic resonance
measurements. Moreover, we highlight the influence of the bulk states as well
as the effect of the finite linewidth of the Shiba state on the magnetization
dynamics. Finally, we demonstrate that the torques are a direct measure of the
even and odd frequency triplet pairings generated by the dynamics of the
magnetic impurity. Our approach offers non-invasive alternative to the STM
techniques used to probe the Shiba states.
