Smartphone applications have become an essential tool for museums because of their positive impact on visitor experience. However, smartphones can potentially distract visitors from the exhibit, crippling the hands-on experience. In this study, we present SurfaceLens which is a smartphone-based peripheral device enabling near-surface spatial interaction with exhibits. SurfaceLens detects proximity, location on the surface, and orientation of the device while a visitor moves it along the surface of exhibits like using a magnifying glass. It provides an information space and audio-haptic feedback reflecting its location and orientation so that the visitor can feel like seeing-through the exhibit. We compared this near-surface spatial interaction with on-screen touch interaction to investigate their effect on visitor experience and behaviour. The results indicate that SurfaceLens provided a more intuitive and transparent understanding of the content when used as an observation tool. Moreover, narrowing down the distance between visitors and exhibits promotes exploratory behaviours.