There are 2 audio outputs on a H9.
So one could used for CV out, the other for Gate out.
Or, internal cv/gate algo converter to midi out…
So we can use a guitar or a bass (or any instrument indeed) as a master keyboard to play an external synthesizer.
I know an Eurorack module named DISTING ( http://www.expert-sleepers.co.uk/disting.html ) that is basically similar to the H9 (multi fx) and can track any audio signal to convert to CV/Gate or midi.