Replacing CR2 battery with usb?
USB ports will produce 5 volts, which is more than the 3V battery produces.
Here's what Wikipedia says about USB output power:


  The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire to power connected USB devices. A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0. 5 volt half an amp.


This means that to use the microphone with USB power, you'd need to have a voltage regulator that drops the voltage from 5v to 3v.The NJU7211L30-ND regulator will probably do the trick.

You could also just buy the battery at a site like this one for around the price you'd pay for a voltage regulator. It's entirely up to you.

Good luck!