There are many ways of achieving this depending on which manufacturer you use and if you are using addressable or non-addressable systems.
Below are examples of a few of the many options available:
Platform sounder - These are made by virtually all the sounder manufacturers and are intended to fit under virtually any detector/base combination, addressable or non-addressable. They connect to the normal panel sounder circuits.
In respect of Apollo equipment:
Non-addressable combined sounder/detector base. Series 65 base with in-built sounder. Wires to normal panel sounder circuits.
Addressable combined sounder/detector base - XP95 base with in-built sounder. Addressable and loop-powered.
There are also options in the Apollo Explorer range.
Rafiki manufacture a device that is a combined smoke/heat/sounder.
There is also a manufatcurer who make a device that is a combined smoke/heat/sounder/strobe/emergency light/public address speaker!
p.s Hammer are you an irons supporter?