The eye radical (Kangxi 109) gives the indexing slot. On the zháo reading the eye-of-contact image fits 'something reaches you, lands on you, makes contact' — catching cold, catching fire, hitting the mark. The same character
着 also appears as
着 (aspect particle),
着 ('to wear') and
着 ('a chess move'); the four readings share one glyph but split the meaning across separate dictionary entries.