This is identical to right-clicking with a 2-button mouse. You may release the Control key after clicking. This method works for a 1-button mouse or MacBook trackpad, or with the built-in button on the standalone Apple Trackpad.

The example below is a contextual menu in the Firefox browser.

Under the Apple menu, click “System Preferences” and then “Mouse”. Change the setting to enable “Enable Secondary Click”. After doing this, you’ll be able to click the right-hand side of the mouse, like a regular right-click button.