Adding pins at start & end index of Text Selection

Hi,
I am struggling with adding pins on startIndex and endIndex of text selection.
I want to add handles when user select text , so that user can edit selection using pins .
Please refer attached video to better understand the functionality I want to achieve.
It would be great if you can provide me some direction , in which I should move in order to achieve required feature or any sample project will be of more help.