Curtains
One option for an enclosed area is to install a retractable screen that can be pulled aside when needed. For example, if you have a wooden security fence in place, add rails to it and put a curtain on the track. When privacy is needed, pull the curtain around the fence, and when more visibility is needed, simply pull the curtain back to one side and tie it off. This approach keeps a security fence in place while providing flexibility with regard to privacy.
Track Fencing
To completely retract a privacy fence, install a fence that is completely or partially on ground-level tracks. For example, you can purchase lightweight aluminum chain-link fence sections. Attach the sections together and put them on a track--when you need a fence, pull the sections around the track and secure it to a pole or wall; when the fence is not required, pull it back to the side.
For greater versatility, instead of tracks, add sturdy wheels to the base of chain-link fence sections. With secure hinges connecting the sections, you can wheel the fence to enclose an area or to open it up. The wheels permit a broader range of options, although the stability of the fence may be reduced unless sections are attached to poles or other fixtures.
Louvers
In lieu of retraction, another strategy for mixing security and privacy is to add louvers to the fence. A wooden fence with slots on hinges provides security while allowing for varying degrees of privacy. Put wood-slat louvers between fence posts and hang them much like a venetian blind--you can adjust the angle of the slats to provide different levels of openness to the outside.
Collapsible Fencing
Consider collapsible fencing for times when a solid, fixed fence is needed but full-time privacy is not. A collapsible fence is composed of two sections--a solid bottom piece and a top piece that slides up and down, retracting into the bottom piece, much like a window pane. When privacy is needed, raise the top piece and lock it into position, and lower the top piece when you prefer a more expansive view. One benefit is that you can choose which sections of fence are open and which retain the privacy screen.
Fabric Fencing
Install poles with a spring-tensioned tube attached. Around this tube wrap a cloth with hooks or other points of connection. To expand the fence, pull the cloth to the next pole and attach it; to retract it, disconnect the cloth and wind it on the spool.