Sub selectedEndnotes()
  ' Loop through selected endnotes.
  
  Dim eNotes As Endnotes
  Dim eNote As Endnote
  Dim rng_selected As Range
  Dim rng_marker As Range
  
  Set eNotes = ActiveDocument.Endnotes
  Set rng_selected = Selection.Range
  
  ' If nothing is selected, show a message
  If rng_selected.Start = rng_selected.End Then
    MsgBox "Please make a selection."
  End If
  
  Debug.Print ("The following endnotes are in selection:")
   
  For Each eNote In eNotes
    Set rng_marker = eNote.Reference.Characters.First ' Get marker range
    ' Only process endnotes whose marker .Start is between selection range.
    If rng_marker.Start >= rng_selected.Start And rng_marker.End <= rng_selected.End Then
      ' ---- Do whatever you're going to do to each endnote here. ---
      Debug.Print (eNote.Index)
    End If
  Next eNote

End Sub