We present a novel non-contact ultrasound (US) and photoacoustic imaging (PAI) system, overcoming limitations of traditional coupling media. Using a long coherent length laser, we employ a homodyne free-space Mach-Zehnder setup with zero-crossing triggering, achieving a noise equivalent pressure of 703 Pa at 5 MHz and a -6 dB bandwidth of 1-8.54 MHz. We address phase uncertainty inherent to the homodyne method. Scanning the non-contact ultrasound probe enables photoacoustic computed tomography (PACT). Phantom studies demonstrate imaging performance and system stability, underscoring the potential of our system for non-contact US sensing and PAI.