A button has a name and a Caption which may be different.  this code get both
name and caption.

Sub Getbutton()
  For Each but In ActiveSheet.Shapes
     If Left(but.Name, 13) = "CommandButton" Then
        MsgBox OLEObjects(but.Name).Object.Caption
     End If
  Next but
End Sub

First, if you really meant commandbuttons (those are from the control toolbox
toolbar), then you don't assign the macro.  

If you doubleclick on one of these commandbuttons while in design mode, you'll
see that it has an event associated with it:

Option Explicit
Private Sub CommandButton1_Click()
End Sub

If you meant buttons from the Forms toolbar, you could use code like:

Option Explicit
Sub testme()
   
   Dim myBTN As Button
   
   For Each myBTN In ActiveSheet.Buttons
       If myBTN.OnAction = "" Then
           MsgBox "No macro assigned to " & myBTN.Name
       Else
           MsgBox myBTN.OnAction & vbLf & "is assigned to " & myBTN.Name
       End If
   Next myBTN
   
End Sub