parapet on a city wall
陴 refers to a parapet, a low protective wall or rampart built on top of a city wall for defense.
陴 combines ⻖ (hill, mound, or wall) with 卑, which likely contributes the sound. The character originally referred to a low wall or parapet added to a city wall.
The left side ⻖ suggests a wall or mound, and the right side 卑 looks like a low structure. Picture a low parapet built on top of a city wall for defenders to hide behind.
For ヒ, imagine a soldier behind the parapet saying 'He!' to warn others: 'He!' -> ヒ, as he peeks over the low wall.