I want my legend which is now in the form of the left bar in the following image, to be shown in the form of the bar in the right side.
I couldn't find anything related for arcGIS.
Does anyone know of something?
To keep the legend "live" (rather than drawing it as graphics), divide the Contours layer into 3 layers in your map. One layer is for values >=12 and will appear at the top of the legend, one is for values <= 1 and will appear at the bottom of the legend, and one is for the values in between. The "Top" and "Bottom" layers will have custom patches in the legend.
Custom patches are loaded to a Style using the "New Legend Patch Shape" command. This command must be added as a button to any toolbar before creating the patches. Use the steps below.
Click Customize > Customize Mode from the main menu. Click the Commands tab on the Customize dialog box. Scroll through the Categories list and click Page Layout. Scroll through the Commands list and click and drag the New Legend Patch Shape command to any toolbar.
To create a custom patch for the Top layer, draw a triangle pointing up as either a graphic element or a polygon in a feature class. While it is selected, click on your new button for the "New Legend Patch Shape" command. Make the correct selection in "Patch Shape", and turn off "Preserve Aspect Ratio". Save the patch by clicking on "Add to Stylesheet" and close. Rotate the selected element or polygon 180 degrees and repeat to get a custom patch for the Bottom layer.