Does my intention for Qurbani need to be verbal?

The short answer: no, your intention does not need to be verbalised. In the Hanafi school the niyyah for Qurbani is an act of the heart. What matters is that you resolve, before the animal is slaughtered, that this slaughter is being carried out as a sacrifice (udhiyah) for Allah's sake.

That said, the scholars of the Deobandi tradition recommend articulating the intention aloud so the slaughterman knows to pronounce the appropriate name and takbir. If you are sending your Qurbani through us, our team carries the intention on your behalf once you have confirmed your booking.