逮 (dǎi) is colloquial for 'catch/grab.' In the formal compound 逮捕 (dàibǔ, to arrest), it is pronounced dài. When used alone as a verb meaning 'to catch,' it's pronounced dǎi.
mistakes
The pronunciation changes by context: dǎi when used alone (逮住 dǎizhù) and dài in the formal word 逮捕 (dàibǔ). Don't mix them up.
