How do you say "I hear you" meaning "to sympathize with; to understand the feelings or opinion of" (Wiktionary; see also tFD, Macmillan, ELU, Urban). Do you need a (preposition and a) pronoun, some complement or just a verb and which verb is that (comprendre, entendre, sympathiser)? Do you say something different if it's used "as a prelude to disagreeing with what has been said" (third example)? Take for instance the following examples:
You're tired of all the ads on TV? I hear ya.
I hear you, honey. I know you're in a lot of pain right now.
I hear you, but we just can't afford to make any big changes like that at this time.
I hear what you are saying about the strength of feeling on this issue.