Socket is just position points on mesh, which isn’t something that can be “taken”, but actors and components can be attached to them, once you do that actor or component will align it self to socket on every frame. So you should check attached actors or components.
Maybe try to keep track if something is attached to socket by yourself with bool varable. Make functions to attach and deattach to specific socket and use them so bool seamlesly change and you can use that information somewhere else as you want.