I see that the cartridge has an entrance of sound, is possible to use it like entrance of DCPM or similar?
http://wiki.nesdev.com/w/index.php/Cartridge_connector
Only the Famicom and Famicom-like devices have the ability to mix in audio.
Other than the FDS, there were only a
few games that added expansion audio music, and another small handful that added dedicated speech playback ICs.
On the NES, Nintendo expected audio to be mixed in on the expansion port. It's far too expensive to make the connector in a small quantity (other than labor intensively by hand, as Chkyn was doing), but at least for audio, INL has come up with an (IMO) brilliant idea for a jumper board that can just slot in and connect the audio pins. It's very inexpensive to build, can be as few as 4 parts if you used a fixed value for the mixing resistor. I'm still holding out hope that all NES systems' audio have roughly the same amplitude.
In other words, I think it's a good time to start talking about audio input on the NES. I've got a couple audio projects in the works.