Concept: If you remove the link between image and mask, both can be moved independently.

1. Open Photoshop. Open Image to work with masking link option.

2. Using Elliptical Marquee tool and Reveal selection command, create the following mask on the image.

3. There is a small link between the image and the layer mask thumbnail shows that the layer mask is linked to the layer. It is indicated with the red arrow in the figure.

4. Now click the small icon of the link to remove the link between the layer and the layer mask. When you click the icon, it will be vanished. Now there is no link between the layer and the layer mask.

5. Select the Move Tool and Click the layer thumbnail. Start dragging the move tool on the image. You will find that the layer mask is stationary and the image is moving inside the layer mask. You can observe the movement of image in the layer palette also.

6. Now click on the layer mask thumbnail and again drag the move tool on the image. You will find that the layer mask is moving and the image is stationary.