How to switch between default and custom brush

Hello guys. I know you can switch from your custom brush to the default brush by pressing ESC, but is there any way to switch back to the custom brush from the default brush? Or does it just get deleted when you switch to the default brush? I’d like to be able to switch back and forth between my custom brush and the default brush if that’s possible.

you can click on the brush preview on the top bar, there yoiu can see your cursotm brushes