At 6th level, you can hit a hidden cluster of nerves on a creature with precision, temporarily causing them to become mentally malleable. If you hit a creature with an unarmed attack, you can spend 1 ki point to force them to make a Charisma saving throw. On a failed save, the creature is unable to speak a deliberate lie and all Charisma checks directed at the creature are made with advantage for up to 10 minutes. You know if they succeeded or failed on their saving throw.
An affected creature is aware of the effect and can thus avoid answering questions to which it would normally respond with a lie. Such a creature can be evasive in its answers as long as the effect lasts.