Custom Control WPF - Combobox with search bar and listview

I am trying to recreate a wpf control I see in alot of software I use. From my research online it seems Custom Control is the way to go. Here is an image of the wpf control: The final goal is to use this control into a datagrid template column to allow user to modify cells in this fashion. I am unable to find a starting point or an example to build up on. Perhaps this is already done and someone can share this with me? Any pointers? Thanks.