Examples

White can sacrifice the exchange with Rxf6+.
Recapturing lures the king to f6, where it can be attacked with the fork Ng4+, giving check and attacking the rook on e3 at the same time.
After capturing the rook, in the end White has won a knight and is a knight up in a winning endgame.

Sometimes a decoy can be combined with additional motifs:

The queen on b8 is protecting the knight on d6, and the square e8.
It is overloaded, and White can win with Qxd6!, combining decoy and deflection.
After the queen recaptures with Qxd6, it is deflected away from protecting e8, and also decoyed to d6.
White can then win the queen back with the royal fork Ne8+, having won a knight in the end.
This combination of decoy and deflection happens quite frequently, even in games of strong players.

Related combinations

Trade into fork is similar to decoy into fork, but the first move is a trade instead of a sacrifice. It is also possible to decoy a piece to a square where it can be attacked in a subsequent tactic other than a fork. And you can decoy the king into checkmate.