If you have an outlet or set of outlets under your sink and you are unsure which outlet (or if both) are controlled by a switch, you can perform a simple test.

Plug your phone into whichever outlet you would like to test.

If your phone shows that it is charging, it is an unswitched outlet.

If it does not begin to charge, it is likely a switched outlet. Turn on the switch that controls the disposal under your sink and if your phone shows it is now charging that confirms that it is a switched outlet.