- I have difficulty finding my socks in the morning.
- I have difficulty in finding my socks in the morning.
Are both the sentences correct? Is there any difference between them?
Both the sentences are correct grammatically, without any difference in meaning.
However, the former, without the preposition "in" after difficulty, is more common than the latter.
Only the first sentence is correct because that's the standard idiom that all use to say that they have trouble doing something. As for the second sentence, that one is not natural and sounds kind of wrong, if you ask me.
You can use the following idioms to mean the same thing (they are absolutely interchangeable with your example).
to have trouble doing something
to have problems doing something
to have no problems doing something