For some reason I found it difficult to find what I needed about the USB Ducky in the past but there is a lot of content now. Below are some resources I wanted to keep handy.

This worked great for creating injection code for the Ducky:

https://payloadstudio.com/community/

There is some great documentation on examples and how to use certain keystroke combinations here:

https://docs.hak5.org/hak5-usb-rubber-ducky

Sample Payloads:

https://github.com/hak5/usbrubberducky-payloads