Pull-out mechanisms for different common steel fibers were investigated using adapted pull-out tests performed in-situ in an x-ray micro tomograph (µXRT). High-resolution volume images from the µXRT scans enable clear visualization of aggregates, pores, the fiber and the fiber-matrix interface. Furthermore, the natural density speckle pattern from aggregate distribution and pores was found suitable for Digital Volume Correlation (DVC) analysis. From the DVC results it was possible to visualize and quantify the strain distribution in the matrix around the fiber at the different load levels up to final failure, being marked by either pull-out or fiber rupture. This study demonstrates that strain measurements within the concrete matrix can be obtained successfully using µXRT imaging and DVC analysis, which leads to an increased understanding of the interaction mechanisms in fibre reinforced concrete under mechanical loading.