About the Trackpad Handwriting input source on Mac
If you have a trackpad, you can use the Trackpad Handwriting input source to enter Chinese (Traditional or Simplified) or Cantonese characters and punctuation with your finger.
When the Trackpad Handwriting window is open, you can’t see or move the pointer on the screen. To use the pointer without closing the window, press the Esc (Escape) key; to resume handwriting, click anywhere in the Trackpad Handwriting window. To close the window, press Control–Shift–Space bar or click Close in the top-left corner of the window.
To learn how to use Trackpad Handwriting, switch to a Chinese or Cantonese input source in the Input menu, choose Help from the Input menu, then search for “handwriting.”