Not all of Microsoft office support Math Convert function.
1. Completely install the XP Pen driver for your tablet and the open the PenTablet Settings and test for pressure. If on Windows, make sure Windows Ink is enabled.
2. Open Office 2019 Word
3. Go to the "Pens/Draw tab- Ink to Math Convert".
4. Write Math equation on the Main input Controller then click the "Insert" button.
5. Go to the "Pens/Draw" function and you can sign or hand-write on the page.