[SalesForce] Retrieve globalpicklist/globalvalueset without SOQL

Schema information isn't available via query, however there is an API for it. Depending on what type of development you're doing:

• Apex methods
• SOAP API
• REST API
• Metadata API

They all work a bit differently so if you have specific questions about using one of them it might be best in a followup question.

You should be able to get the data by querying (Tooling API):

SELECT Metadata FROM CustomField WHERE TableEnumOrId = '<Table Name>' AND DeveloperName = '<FieldName>'

The valueSet attribute of the Metadata field will contain the name of the global picklist used, if any.

Example (40.0):

{
  "size" : 1,
  "totalSize" : 1,
  "done" : true,
  "queryLocator" : null,
  "entityTypeName" : "CustomField",
  "records" : [ {
    "attributes" : {
      "type" : "CustomField",
      "url" : "/services/data/v40.0/tooling/sobjects/CustomField/00N500000041HS5EAM"
    },
    "Metadata" : {
      ... // excluded for brevity
      "valueSet" : {
        "controllingField" : null,
        "restricted" : true,
        "valueSetDefinition" : null,
        "valueSetName" : "A",
        "valueSettings" : null
      },
      "visibleLines" : null,
      "writeRequiresMasterRead" : null
    }
  } ]
}

Note that this will be the "developer" name of the valueSet. So, for example, above, my value set is called "A".