Understanding capacitors and pre-amp configuration in this tone decoder circuit
They are RC filters used to bypass the supply rails for the FET preamp inside the microphone and the BJT stage.

In this way the supply rails for these two stages are better decoupled from the rail for the 567 IC and from each other. This helps keeping the rails stable for those sensitive input stages, otherwise the unavoidable (tiny) variations of the rail voltage due to higher power stages may couple back to the input stages as noise.

From another point of view, you can see the capacitors as a reservoir of energy for the stage they decouple (note that the BJT stage has a 10 times bigger cap because it needs more power to work), whereas the 1k resistors act as a barrier against supply variations coming from the 5V rail. Therefore small variations in the 5V rail voltage will be attenuated when seen as voltage variations across those reservoir caps.

BTW, it seems that the schematic has an error: the 470k resistor right leg should be connected to the collector of the BJT, but the schematic is missing a dot on that junction. As it stands, that resistor goes straight into pin 3 of the IC through that 1uF cap, which is weird.