Genesis 34 tells about Shechem's rape of Dinah and the events that follow. 34:5 says that Yaakov heard ( שָׁמַע) about this (and didn't act immediately).
He didn't hear it from Dinah because she didn't come home (her brothers go to rescue her later). Shechem and Chamor came to negotiate a wedding, but the text implies that came after Yaakov heard. How did Yaakov hear? Did Dinah have a hand-maid who was with her and came back, and the text just doesn't mention that? Were the townspeople gossiping and word reached him that way? Did Chamor tell him and the text isn't strictly in order?
Rashi is silent on this verse, as is S'forno (at least in the English translation I have access to), and I didn't find anything in the chumashim I have ready access to nor via Google.