charge customer per hour for consulting

Unfortunately, this sort of functionality is not built-in to Zoom. 

A workaround would be to use scheduling tracking tags to keep track of meetings scheduled for each client, then run reports to tabulate how much time you've spent with each client and bill them accordingly. 

There may also be an integration on the App Marketplace that would do some of this for you, but I am not aware of anything specific to these needs. 

Hope that helps and please make sure to mark the solution as accepted if this information is what you needed.