You could use the appropriate Simulink support package; https://www.mathworks.com/help/supportpkg/android/ref/tcpipsend.html if you are looking to use MATLAB to generate the code that will run as the mobile app.
See also https://www.mathworks.com/hardware-support/android-sensor.html if your data is Android sensor data.
You can use tcpclient() from MATLAB itself if the mobile app is willing to act as a server.
If the mobile app is to act as a client and MATLAB is to act as a server, then you need either the Instrument Control Toolbox so you can use tcp() or udp() as a server, or you need the tcpipudp File Exchange contribution.
