You can draw a drop-down button on a combo box control in the specified state, on the specified graphics surface, and within the specified bounds with the help of ControlPaint.DrawComboButton Method using vb.net
You can use ControlPaint.DrawComboButton Method like as :
Public Shared Sub DrawComboButton ( grp As Graphics, rect As Rectangle, state As ButtonState )
Example
Following example draw a drop-down button on a combo box control on windows form:
Private Sub Form1_Paint(ByVal sender As System.Object, _ ByVal e As System.Windows.Forms.PaintEventArgs) _ Handles MyBase.Paint ControlPaint.DrawComboButton(e.Graphics, New Rectangle(50, 50, 20, 20), ButtonState.Checked) End Sub