  We propose to detect signals from quark orbital angular momentum (OAM)
through exclusive $\pi^0$ production in electron-(longitudinally-polarized)
proton collisions. Our analysis demonstrates that the $\sin 2\phi$ azimuthal
angular correlation between the transverse momentum of the scattered electron
and the recoil proton serves as a sensitive probe of quark OAM. Additionally,
we present a numerical estimate of the asymmetry associated with this
correlation for the kinematics accessible at EIC and EicC. This study aims to
pave the way for the first experimental study of quark OAM in relation to the
Jaffe-Manohar spin sum rule.
