Embed your MATLAB code inside a Simulink model that uses the Android https://www.mathworks.com/help/supportpkg/android/ref/audiocapture.html Audio Capture block. Note that during simulation (when model is not deployed to Android) the input will be all 0.
Alternately, write a Simulink model that uses the Android Audio Capture block together with an Android https://www.mathworks.com/help/supportpkg/android/ref/udpsend.html UDP Send block. Then on the MATLAB side, use https://www.mathworks.com/help/instrument/udpreceive.html UDP Receive. (Note: if you do not have Instrument Control toolbox, look in the File Exchange for the tcpudpip contribution.)
