The detective caught sight of a crucial clue that everyone else had missed.

caught 是动词 catch 的过去式，意思是"抓住、捕捉"。 sight 是名词，意思是"视线、看见的东西"。 of 是介词，表示所属关系或来源。 caught sight of 是一个固定短语，意思是"突然看见、注意到"，强调偶然发现。