The Good-Morrow has a basic iambic pentameter template, that is, there are five regular beats and ten syllables in each line except for the last line of each stanza which has twelve, so count as hexameters.
But there are odd exceptions here and there - some lines with an extra beat for example (11 syllables), others with trochees, spondees and anapaests, which alter rhythm and so bring added interest for the reader.
John Donne was famous for not completely yielding to the formality of poetry that was high valued during his time.
Source: Owlcation https://owlcation.com/humanities/Analysis-of-Poem-The-Good-Morrow-by-John-Donne