The MAX4466 Microphone module is a breakout board with a 20-20KHz electret microphone and the MAX4466 preamplifier IC.
On the back of the board is a small trimmer that allows you to adjust the gain from 25x to 125x.
 
The module runs on 2.4…5.5V with a very low quiescent power supply current of <24μA. For good performance, use the ‘quietest’ supply available. This would be the 3.3V pin of an Arduino or ESP32.
Note that the maximum output voltage on the OUT pin is from 0 V to VCC.
If you connect the output to the Analog-Digital-Converter (ADC) of your microcontroller make sure that it can handle the maximum output voltage! The output will have a bias of VCC/2. So when it’s perfectly quiet, the output voltage will be VCC/2 V.
 
You could also connect the VCC pin of the MAX4466 module to 5V and you would get a better resolution on the analog input A0 but the input would be a bit more noisy.
If you use an ESP32 you must run the MAX4466 module on 3.3V, since the maximum output of the module is based on VCC and with 5V as power supply, the voltage on the analog input would be too high!