I personally wouldn't use those for anything. They are expensive and I can't find a spec sheet anywhere.
I've found a very similar looking motor that is 64 rpm instead of 2 rpm:
Free shipping.12V/64rpm/2.5kg.cm dc Gear motor,dc worm motor,Electric windows motor,micro motor-in DC Motor from Industry & Business on Aliexpress.com

And that has some specs. Look at the price, look at the torque and then compare it to the specs for the mg996r at servo database:
TowerPro MG996R Servo Specifications and Reviews

Forgive me as we don't have a lot of information to go on but do you understand, what dc motors, steppers and servos are and do you know how each of them works?

Try watching this video:

https://www.youtube.com/watch?v=-XSXfqd1N58

A servo is just a DC motor, geared down with an absolute positon device and some control electronics. Sure you could use steppers to do what you want but as you design it you will figure out that:

Quote Originally Posted by edgas10 View Post
for diferent bands i need that the positions can be stored, to be easely adjusted.
You need to store the microphone positions, this means you need a computer. The computer can be a normal big box PC that you are familiar with or it could be a micro controller like an avr or pic (ie an arduino which has already been suggested).

In order to move from position A to position B, you need to know where the microphone actually is in relation to positions A & B. You can use servos which already come with this feature built in or you can use steppers and spend a load of money and time creating your own custom absolute position encoder.

You need a way of translating real world microphone positions into positions of 5 motors, welcome to Inverse Kinematics.

Arduino Robotic Arm with Inverse Kinematics - Towers of Hanoi - YouTube


If you aren't happy with the performance of hobby servos you can often upgrade the electronics using openservo, or if you have lots of money you can damage your wealth and go for dynamixel servos.

:::ROBOTIS:::