KickPo

KickPo is an audio to MIDI effect that outputs either a note-on event (gating only, does not track pitch), a control change toggle (0/127), or a control change envelope sweep.

It was made for a sustain pedal to be plugged directly into an audio interface, or a guitar patch cable to be stepped on for toggling. Other sources that output volume may work, a microphone, headphones plugged into an input, other footswitches.