Quasi-static-toggling (QST) mechanical energy harvester (MEH) can slowly accumulate a certain amount of mechanical potential energy. After the triggering position, it releases and converts the stored energy into useful electricity in an instant. It was designed into micro-generators for powering some ultra-low-powered Internet of Things (IoT) devices. This short paper introduces a 4-in-1 QST-MEH design. It uses a compact and deformable iron cantilevered beam to inclusively embody four key elements, i.e., an iron core, an energy-buffering spring, a rebounding spring, and a mechanical lever, which form a monostable QST electromagnetic generator. Compared with the existing designs, the proposed design reduces the component number to the most extreme. It largely helps reduce manufacturing and assembly procedures toward low-cost implementation and reliable operation. Experimental result shows that about 0.25 mJ of energy can be harvested from each round of press-release action with the experimental prototype. Such an amount of energy is sufficient to power an iBeacon Bluetooth low-energy (BLE) transmitter for motion-powered IoT applications.