But I am confused about the pins which are responsible for sending the measurement values to the LCD display. Because once I find out which pins/circuit wires are responsible for sending for sending the data, I can very easily feed the same to arduino.
You should use a multimeter equipped with an isolated serial interface for that purpose. The isolation of the serial interface is important to avoid unwanted grounding of the multimeter circuit.
If you use the multimeter with a connection from the LCD to the PC to measure the power grid voltage (110 or 230 V AC), you may get an electrical shock and destroy the multimeter or the PC or even both.
Using the serial interface for data transfer is easy (been there, done that, but having a good knowledge of asynchronous serial data transmission). Using the LCD signals would be very tricky and difficult.