You can add a gap in the extension line, if that's what you're asking about. Right-click on the extension line, choose Dimension Object + Create Interruptions
the dimension value location should happen automatically, based on which drafting standard you're using. ANSI or ASME will locate the dimension centered on the dimension line, with a gap. (ISO locates the value above the solid dimension line) Use File + Page Setup to choose which standard you're using.