  The existence of exotic spin-dependent forces may shine light on new physics
beyond the Standard Model. We utilize two iron shielded SmCo$_5$ electron-spin
sources and two optically pumped magnetometers to search for exotic long-range
spin-spin-velocity-dependent force. The orientations of spin sources and
magnetometers are optimized such that the exotic force is enhanced and
common-mode noise is effectively subtracted. We set direct limit on
proton-electron interaction in the force range from 1\,cm to 1\,km. Our
experiment represents more than ten orders of magnitude improvement than
previous works.
