its possible to read serial ouput from ICSP or Tx Rx pin instead from USB port? If it's possible how? thanks for reply
The TX and RX pins are connected directly to the USB to UART adaptor embedded in the board (an ATMega16U2 on the Uno R3, or a CH340G on a cheap Chinese clone). Anything that goes through the USB also goes through those pins.
You can also, if you must, use SoftwareSerial to get serial on any other pair of pins of your choice.