This paper is principally intimate the updated technology of burglar alarm using sensor. Here magnetic field sensing element plays an important role in providing the range of the magnetic field. In recent days robbery in home and department stores are increasing more frequently. Due to this people feel less secure in their life. Burglar alarm is the technology that uses sensors to detect and measure the magnetic field strength. To avoid this type of scenario here comes burglar alarm system. This alarm indicates whether there is any theft in home, bank, office, jewelry shops, grocery stores and in many other places. This updated alarm system includes a sensing element which will detect magnetic field and translate them into commands for the alarm to initiate the move. This paper offers an updated system of burglar alarm using hall sensor. The sensor detects the magnetic field and passes the information about magnetic field strength and the output is displayed in the 16x2 LCD display.