Maybe and May be

Both have similar meaning. The difference is whether you are using it as a verb (modal verb) or an adverb.

"maybe" is an adverb that means "perhaps" or "possibly".
e.g.:
Maybe I am wrong. (= Perhaps I am wrong, or I am possibly wrong).

"may be" is a modal verb that means "(is, am, are) possibly" or (is, am, are) perhaps".
e.g.
I may be wrong. (= I am possibly wrong, or = Perhaps I am wrong).

Therefore, when "maybe" is used, a main "verb" must also exist in the sentence. When "may be" is used, it itself is used as the main verb, so another verb must not exist in the same sentence (clause).

One easy way to tell whether "maybe" or "may be" should be used is to substitute it with "perhaps"; if it makes sense, then it should be "maybe".
e.g.
If we change "I may-be wrong" to "I perhaps wrong", the sentence becomes a fragment, and it does not make sense, so it should be "I may be wrong".