|This is a Wiktionary experiment, and should not be taken to be official, agreed upon, functioning, or even a good idea.|
This feature currently requires the user to opt in, either by manually importing 'User:Atelaes/pronunciationCustomization.js' or by checking 'Allow conversion of IPA to other formats' on WT:PREFS. Currently, only SAMPA is functioning, but others may be added in the future if the community shows interest in the project. If you do not see any options beneath the 'Options' header, then either you do not yet have the JS enabled or you need to refresh your cache.
While the standard format for representing sounds on Wiktionary is IPA, users can customize the format which is presented to them. It should be borne in mind that IPA is the default for a reason, as it is the industry standard, as well as the most robust and precise system.