I can't tell if strRng is a Range or a String.

I can't tell if the User is Selecting 1 cell or several.

This code, (which might not work,) is based on the User only Selecting one cell at a time.

Option Explicit

Private Sub Worksheet_SelectionChange(ByVal Target As Excel.Range)

  Dim SelectionRange As Range
  Set SelectionRange = Range("A:A")  'assign as needed
  
  If Target.Count <> 1 Then Exit Sub
  
  If Not Intersect(Target, SelectionRange) Is Nothing Then
    ActiveSheet.Shapes.Range(Target.Text).Fill.ForeColor.ObjectThemeColor = msoThemeColorAccent2
  End If
  
End Sub