Din Sync shows how to use the Free SyncKontrol app from Korg with your modular synth. He explains that at the very least you will need to amplify the output and ideally use something like a Maths to control the pulsewidth of the clock, though it will work without one if amplified. It's really just a click sound. The signal is not very strong though so if you a feeling ambitious you can use the included schematic from Din Sync shown below to build a DIY noninverting amplifier.
The schematic for building a DIY noninverting amplifier.

More info at http://www.dinsync.info/
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