I am planning to amplify AC signal (without sacrificing dynamic range) using MCP602(Microchip), but the datasheet shows input voltage is from 2.7V to 6.0V. My question is can I use negative supply in the MCP602, instead of ground. Do dual supply op-amps are different from signal supply op-ams, or can we use both interchangeably.
Yes, but the difference between the positive and negative supply voltages must be between 2.7 and 6V.
You can also AC couple the input and use divider resistors to generate a voltage mid-way between V+ and V- without using a split supply.
You could also use a resistor divider to generate Vcc/2 and connect the ground side of the AC input signal to that instead of using the AC coupling capacitor and R1-R2 divider.