Below the keyboard dropdown, you should see a list of four keys: Caps Lock, Control, Option and Command. While these are fairly important keys when using macOS, some users may hold the Escape key in a higher regard. We’d avoid reassigning Control, Option or Command and opt for reassigning Caps Lock as you can achieve the same effect by typing while holding the Shift key.
Either way, select the key of your choice and select Escape from the drop-down window. Once you’re done, simply click OK to save your preferences and trial out your new Escape key!