Micromobility refers to small, lightweight vehicles such as shared bicycles and electric scooters (e-scooters). Recently, shared micromobility services see increasing deployment in urban areas, especially for trips where the travel distance is considered long for walking, but not worth driving a car (e.g., to avoid parking). A key question to ask when deciding whether to deploy a shared micromobility service in an area is: how much car traffic can be reduced during peak hours if this service is deployed? This work answers this question by agent-based transportation simulation. The key contribution is to generate a realistic synthetic population of transportation users in the target area along with their travel day-plans, using an area-specific travel survey plus openly available data sources. We demonstrate our approach through a case study on the deployment of dockless e-scooters in Birmingham, AL, with a demo at https://youtu.be/zh_mHQ6ck4U.