This should work (I tested it and seems to be doing what you need).
Ctrl + H, . , Ctrl + T, , . -, Ctrl + T, False.
private bool isCtrlHPressed;
private void txt_callerName_KeyDown(object sender, KeyEventArgs e)
{
if (isCtrlHPressed && e.KeyCode == Keys.T && e.Modifiers == Keys.Control)
Console.WriteLine("^");
isCtrlHPressed = (e.KeyCode == Keys.H && e.Modifiers == Keys.Control);
}