There is one little problem. You can’t.
Mooshimeters original specs told that it could measure frequency, but my guess is that it ran out of memory before that was implemented. So standalone frequency logging wont probably ever happen..
But. It might be possible to do it on the app. We just need a skilled programmer. Those should be plentiful, but as we have been waiting for one, we have already made a long to-do list for someone that would stand up for the job.. My vote for first task goes to “free math”-channels.
You might want to check this:
while waiting for someone to code what you need for mooshimeter.