Before transporting themselves or traveling through time, the Vorgons activated implants in the sides of their heads.
In the 27th century, two Vorgon criminals, Ajur and Boratus, attempted to steal a device known as the "Tox Uthat", a quantum phase inhibitor capable of halting all nuclear fusion within a star. In order to prevent the Uthat from falling into the wrong hands, Kal Dano, the Uthat's inventor, traveled back in time to the 22nd century and hid it on Risa. Having failed to obtain the Uthat, Ajur and Boratus searched historical records and discovered that Jean-Luc Picard would discover and destroy it in 2366. Traveling back to that point in time, they told Picard that they were security agents and that they wished to retrieve the Uthat for safekeeping. When Picard learned, however, that it was two Vorgons who attempted to steal the Uthat in the first place, he destroyed it using Transporter Code 14, thus fulfilling his role in history. Failing in their quest to obtain the Uthat, Ajur and Boratus returned to their own time. (TNG: "Captain's Holiday")