Partly hidden by his beard, Obi-Wan's lips pull slightly in a smile as the child responds. He was young, and clearly untrained, but the signs were there. As their minds touched, Obi-Wan tried to communicate with the little one. Not with any sort of words, but with feelings.

Over here, little one. Can you find me?

Crouching down next to the ship, the Jedi tried to direct Grogu's attention in his direction. To follow his feelings to the person that was reaching out for him. To use his senses rather than his sight.