The present disclosure relates to real-time surveillance/monitoring of an environment using an Internet of Things (IoT) based integrated device. The integrated device comprises replaceable sensors and programmable image/video capturing device, that are communicatively connected to a processor. The processor correlates sensor data and data related to the images, audios and videos received from the replaceable sensors and the programmable image/video capturing device to validate occurrence of event in the environment. Later, information related to the validated events are transmitted to edge nodes, cloud servers, user devices or other sensor nodes for effective monitoring of occurred events. The integration of programmable image/video capturing device with the replaceable sensors helps in reducing chances of false event detection, as well as allows users to program the image capturing device for detection of various events. Also, integration of various sensors helps in reducing electrical wirings and overall complexity of the device.