Bogaudio RefTone if you want to see it clearly and change it with a knob. Submarine has a few constant chromatic note generators, if you want to change a note, by changing a connection.
I agree with Markus. If moving a cable is OK every time you want to change a note (true constants), then the Submarine modules should work really well.
The SS-212 provides a one octave chromatic scale, and you can set the octave via the context menu. It is only 2 hp.
If you need to cover many octaves and want a single module, then the SS-220 provides a 10 octave chromatic scale, but it is 20 hp
An old fashioned sequencer is kind of ideal for this. in a way.
Oh, and you are fortunate you have fancy kontakt drum kits. But for the less well-heeled there are lots of good free drum kits in SFZ format that play nicely in a free SFZ player.