The easiest would be to prepare a script function on the V-REP side, that your Matlab client can call via simxCallScriptFunction. Inside of that function, you can do whatever you wish.
But the first thing you should do is try to understand what the script attached to that sensor does and how it operates. Only then you can correctly access the sensor data.
Remember that those sensors are examples, and could be created in a very different way.
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