Xiaomi mobile phone does not support the export of its own notes, so you can share notes and save them. Xiaomi mobile phone can use dedicated cloud notes, and the cloud note APP supports exporting all notes to mailbox storage:

Dedication sign is a sticky note software for automatic cloud service of data content, and Android APP can be installed on Xiaomi mobile phone.

When changing the device login account, the data content is automatically synchronized, and the notes can be synchronized across computers, mobile phones, tablets and other devices.

You can manually export all the notes to the mailbox on the cloud note, or you can set a regular export, and the system will automatically export all the notes to the mailbox at regular intervals.