1. Ask the teacher directly: you can send a text message or email to the teacher to express your desire to add WeChat and ask the teacher if it is convenient to communicate through WeChat.

2. Get contact information through other channels: If you can't contact the teacher directly, you can try to get the teacher's micro-signal through other channels. For example, you can ask the teacher's students or colleagues for contact information, or look up the teacher's personal information on the website of the school or college.