There is a module called "Random Task" it has a Gate input which can either be trigger by a Clock/Gate or in this case the Gate from a key press.
This generates a Voltage which has probability, shuffle and Steps/Range controls and also voltage value from 0 to 5v's The output CV goes into a quantizer to keep it in tune. From there it just gets a little mad as it feeds an oscillator which controls a vectoring module, which is modulated by three other oscillators. which in them selves are modulated by a few LFO's. Do you get the picture?
Thanks for the ears @bjornpdx. When you do look in to Modular synthesis be prepared to disappear down a rabbit hole and get lost along the way.