You can use some input methods on your mobile phone to operate. (Such as iFlytek voice input method, or Sogou voice input method, etc.).

Take the iFlytek voice input method as an example:

1. First, open the chat tool WeChat on your phone and click to enter.

2. Select a friend, enter the chat interface, and then select the microphone symbol under the input box.

3. The default voice speaking is Mandarin, select Mandarin to enter.

4. In the options in Mandarin, select dialects and then find Cantonese.

5. Then you can speak in Cantonese, so that Cantonese text will be displayed in the input box.