Security is a key element to support data transmission in a Wireless Sensor Network (WSN). ZigBee is one of the leading communication protocols in the WSN that is now the industry's concern for monitoring and control applications. The security method used in the ZigBee protocol requires a large memory capacity and computing time. This limits the security protocol to meet the real-time requirement for some medical and industrial applications, especially for resource-constrained devices. In this paper, we proposed a secure and lightweight privacy preservation mechanism with a new key generation algorithm using the modified Fibonacci and combination of symmetric and asymmetric cryptography. We have conducted a testbed implementation of the proposed method and also measured and analyzed the processing time, Packet Delivery Ratio (PDR), throughput, delay, and the use of the dynamic memory.