You can use Magic Mouse anywhere within range of your computer. When you need to charge the mouse or if you need to pair it again, connect it to your iMac using a USB-C Charge Cable.
To connect your Magic Mouse to your iMac, see
Click: Press the upper surface of the mouse to click or double-click.
Screen zoom: Hold down the Control key and scroll with one finger to enlarge items on the screen. (To enable screen zoom, in System Settings, click Accessibility, click Zoom, then select “Use scroll gesture with modifier keys to zoom.”)
Two-finger swipe: Swipe left or right to move through pages, photos, and more.
Customize your mouse. To adjust settings such as tracking and scrolling speed, and to enable or customize gestures, click Mouse in System Settings.