Navigate to the location of the spreadsheet.
On the Insert tab, click.
Activate the Spreadsheet button.

Click on an existing Excel spreadsheet.
You can make a new spreadsheet from this page if you don't already have one.
To embed, pick a file.
Press Insert.
If the file contains a chart or table, you can just add that instead of the spreadsheet or just attach the file.
Click the Spreadsheet button.

In the spreadsheet's upper-left corner, click Edit.
You can make any necessary adjustments once the spreadsheet has opened.
If necessary, modify the spreadsheet.
Press Save.
To close, click.

When you come back to OneNote, your notes have been updated automatically.