Optical atomic magnetometers are often bulky and operate at elevated temperatures that impose restrictions on studying biological samples. Here we report a miniaturized Cs-based magnetometer, in contrast to conventionally used K- and Rb-based ones, with high sensitivity. The magnetic shield employed is more compact, and the optimal operation temperature of 37 degrees C is lower than previous magnetometers and is suitable for biological research. Applications include scanning magnetic imaging of functionalized magnetic particles and nuclear magnetic resonance of water. We reveal that the stability and sensitivity of the apparatus are not significantly affected by the absence of a laser stabilization device.