Electromagnetic cloaking with monitors within waveguide plays a pivotal role in minimizing the risk of detection while intercepting sensitive information which holds immense potential in both military and communication sectors. However, the integration of electromagnetic cloaking and monitoring is challenging and even more difficult to realize in waveguide. To address these challenges, we propose a metadevice design method based on the internal multiport method (IMPM) for ensuring effective monitoring while maintaining electromagnetic cloaking in the complex environments of waveguide systems. Strategically adjusting the distribution and arrangement of auxiliary scatterers in proximity to the monitoring apparatus can flexibly regulate the behavior of electromagnetic wave propagation to enhance the cloaking performance of metadevice. The cases presented in the paper validate the designed metadevices that are capable of achieving both cloaking and monitoring for monitors within waveguide systems.