か嗅kaぐgu
1.
To perceive scents or odors by using the sense of smell, often involving the act of inhaling through the nose to identify and distinguish aromas.
2.
To investigate or search for hidden matters or truths, often used figuratively to describe prying into someone else's affairs or secrets.
Example:
犬は見知らぬ人の匂いをかいだ。