Windows allows only one caret per message queue. To add a caret to a control, handle the WM_SETFOCUS message, or the GotFocus event, or override OnGotFocus if you're writing a custom control, and call CreateCaret from the message or event handler. You should also handle WM_KILLFOCUS, LostFocus or OnLostFocus and call DestroyCaret. You will also need to call ShowCaret to make the caret visible, and SetCaretPos to set its position.

        ShowCaret(textBox1.Handle);

    ShowCaret(TextBox1.Handle)

ShowCaret

Private showCaret As Boolean

  showCaret = False

  If showCaret = False Then HideCaret(tb.Handle)

static extern bool ShowCaret(IntPtr hWnd);

Function ShowCaret(ByVal hWnd As IntPtr) As Boolean

ShowCaret(listBox1.Handle);