"Captivating" is a love poem about being completely taken in by another person. The speaker begins with questions: what is it about this person's eyes, or voice, that makes them stop and lean closer? Looking at those eyes feels like wading into deeper water, and the speaker can feel a tide tugging at them. Listening leaves them dazzled and stammering.
Midway through, the speaker turns to how the person carries themselves. "Move" is called too ordinary a word, because everything this person does, from standing to walking to reclining, seems like dancing. The speaker wants to learn it and mirror it. The poem's central idea is a neat contradiction: the speaker feels like a prisoner, yet also set free. Being held by someone's presence turns out to be freeing.
The mood is warm, hushed and admiring. The short, unrushed lines and the final phrase, "quiet grace / In you," give it a calm, reverent feel rather than an anxious one.