There are two ways to select Detail as your camera in Zoom.
If you want to change your camera selection in Zoom when you're not on a call, just head to "Preferences" and click on the Video tab on the left side of the window.
You should see a dropdown menu under "Camera". Click here and select "Detail Camera". If you can't see "Detail Camera", make sure you have Detail installed on your Mac.
You can also change your camera selection while on a call. Just above the camera icon at the bottom of the window, there's a little arrow button. Click this arrow (or press Shift-Command-N) to select a camera. You should see "Detail Camera" as an option in the menu.