The monitoring of processor temperature is crucial to increase its efficiency. One of the novel approaches is use the information not only about the CPU (Central Processing Unit) thermal state, but also about changing environmental conditions. The additional temperature difference sensor to monitor thermal changes in the processor environment is necessary. The sensor dedicated for active heat sink, often used inside laptops, was designed, fabricated and investigated. To fulfill the requirements and to match to the specific shape of the active heat sink, the hybrid sensor was proposed. It was composed of six thermocouples and fabricated using thick-film and LTCC (Low Temperature Cofired Ceramic) technology combined with wire thermocouples. Thick-film/LTCC flat substrates with thermoelectric paths ensured good thermal contact between the sensor and the monitored surface. The thermoelectric wires allowed adjusting the sensor to the complicated shape of the active heatsink. Three different versions of the sensor were realized and compared. All of them seem to be suitable for measuring the temperature difference in the given application and they can be used in further works.