Voice over WI-FI with ESP8266

I was reading about this NSA hack where they use a Samsung Smart TV to record audio data in order to potentially spy on its users: https://wikileaks.org/ciav7p1/cms/page_12353643.html
I wondered on what would it take to build a similar spy microphone that could send audio over WI-FI, be cheap and small enough to hide it.
What I came up is a system that uses one ESP8266(NODEMCU) board, one PIC18F25K22 micrcontroller and one MCP6024 amplifier in order to prove that this is possible.
The system is pretty cheap but not very small.

I built this system on a breadboard and as expected, is bulky. For a proof of concept I thinks it’s good enough.
It could be made smaller by using only the ESP8266 chip instead of all the NODEMCU board, and by replacing the PIC and audio amplifier with smaller chips, maybe their SMD versions, or other smaller chips with the same capabilities. A small battery would also be necessary. Of course, all of them soldered on a custom PCB.”