Electron Microscopes are sensitive to noise of all kinds : Alternating Current (AC) Magnetic Fields, acoustic disturbances, temperature fluctuations and/or disturbances caused by rapid air flow in clean rooms. Therefore, existing and potential room locations need quick and reliable characterization methods for all these parameters. AC noise, in particular, is characterized today by either specialized instruments and handheld meters dedicated to the purpose. Our aim is to find a suitable substitute for these instruments by making an application that uses the in-built magnetometer in smartphones to measure electromagnetic fields. Our research is motivated by the fact that smartphones with considerable computing ability have become ubiquitous enough that they become a viable alternative to some dedicated characterization instruments. Furthermore, a method to characterize these fields can also extend to other applications, such as finding and mapping electrical faults, and touchless 3-D interaction. We will discuss the development process of an iPhone application for quick analysis and recording of electromagnetic noise in equipment rooms for the installation of sensitive equipment. This will cover the suitability of the hardware to the purpose, the sensitivity of the hardware to our measurement criteria, our methods for data analysis and the associated software visualization techniques, and comparison to existing methods. Finally, we cover the limitations and potential applications of the software developed.