Q: Does Apple devices like iPads leave caches in the system? Yes or No.  If yes how can the system caches be deleted?

Yes.

The system or iOS caches are called "Documents & Data" or D&D for short and "Other". They can be seen by connecting your iOS device to iTunes - on the Summary Tab at bottom there will be bar display with details. They cannot be deleted. The only way to reset them is to do a System Restore. A restore will reduce the sizes of D&D and Other but they will start growing again. Apps however have caches that can be deleted. Safari for instance > you can delete All Cookies and Data. For other apps it depends on the App.

System Restore. First backup your device using iTunes. Also import your photos to your computer and copy all important data if possible. Try restoring from backup first and testing it. If it does not help, you may have to restore as New and reconfigure from scratch as the backup could be corrupted. For this reason it is important to have your photos and data saved separately from the backup. Here are the steps for a Restore:

https://support.apple.com/en-us/HT201252

Also these articles help explain the caches:

http://osxdaily.com/2013/07/24/remove-other-data-storage-iphone-ipad/

http://www.imore.com/how-find-and-remove-other-files-iphone-and-ipad

https://support.apple.com/en-ph/HT201656

https://discussions.apple.com/docs/DOC-5142

My pleasure...