Fiber optic distributed acoustic sensing (DAS) based on phase-sensitive optical time-domain reflectometry holds significant potential for monitoring applications in seismic exploration, pipeline integrity, and border security. Conventional straight-fiber DAS systems are inherently limited to detecting single-component vibration signals along the fiber axis. To address this limitation, we propose a distributed helically wound cable (HWC). In this article, we present a theoretical analysis of the fundamental mathematical model governing HWC response and the selection criteria for an optimal spiral wrapping angle. We conducted a pioneering three-dimensional seismic field experiment in Xinghua, Jiangsu, China. An innovative underwater cable deployment scheme was implemented to ensure effective coupling between the cable and the surrounding medium. Experimental results demonstrated that HWC with a 30° wrapping angle yielded single-shot records characterized by a high signal-to-noise ratio and a broad effective frequency bandwidth, and enabled clear identification of shallow reflection events in stacked sections. This confirms the capability of HWC to acquire ground seismic reflection signals. Our findings provide an effective pathway for advancing next-generation fiber optic distributed seismic exploration technology.