Notes in Zoho CRM are always associated to other records such as leads, contacts etc. You can import notes in your account with the Migrate from Other CRM feature using Zwitch. There are two ways you can import Notes using this feature:
Import with the Notes' Parent Entity ID
Import with the Notes' Parent Entity Name. When you select this option, you also need to choose the module from the drop down list.
Here, the parent entity refers to the record that a note is associated to. Please make sure that the records the notes are associated to are already imported into Zoho CRM before you migrate the notes.