Since WooCommerce 2.1+, order notes aren’t listed anymore in the comments section (because yes, WooCommerce order notes are regular WordPress comments). That was something a lot of users asked to change because their comments were messed up with order notes. But Some of you need to bring the notes back in the list, in order, for example, to process searches in order notes.
The good news is that you can bring the notes back by adding a simple line of code in the functions.php file in your theme folder.
Simply copy and paste that code and you’re good!