is it necessary to use sensors with raspberry pi to get real time data?

Hi,

    Not sure if I understand your question. You need sensors on your RaspberryPi to record/store data information. You RaspberryPi is just a board on which you put sensors that can record/store some values. For example, when you say you are retrieving some temperature and humidity values from a RaspberryPi you are actually retrieving values(data information) from a sensor(for example AM2302) on that RaspberryPi.

    Tell me more about your project or what is it that you are trying to achieve.

Hope this helps,

Adrian