Microbes exist in unfathomably diverse, dynamic and intricately structured ecosystems. However, we lack the tools to fully capture the complexity of these microbiomes, which in turn limits our ability to understand their ecology and function. Here, I address these shortcomings by developing new high-throughput measurement tools to characterize microbiomes across functionally distinct axes. First, from a synthetic biology perspective, I leverage the bacterial CRISPR-Cas immune system to enable a new class of population-wide passive recording devices in cells for capture temporally varying signals and horizontally transferred DNA sequences. Second, in the microbiome arena, I develop a new suite of tools (experimental and theoretical) to capture and analyze the spatiotemporal dynamics of microbiomes at macroscopic and microscopic length scales. Taken together, these measurements provide deep insights into the ecology of complex microbiomes, and constitute a suite of powerful new tools to study microbes in their native context.