A locking mechanism and method for selectively fixing and allowing movement of a tip portion of a probe relative to a rigid portion of the probe are provided. The mechanism comprises a locking ball joint for selectively locking and allowing relative movement between the tip portion and the rigid portion and a sleeve about the ball joint. The locking ball joint is locked by the placement of the sleeve in a first position, thereby fixing the position of the tip portion relative to the rigid portion, and released by the placement of the sleeve in a second position, thereby allowing movement of the tip portion relative to the rigid portion.