apex:page controller="SampleWrapperClassForThreeObjects" showHeader="false" sidebar="false"  action="{!displaydata}">  
  <apex:form >  
  <apex:pageBlock >  
   <apex:pageblockTable value="{!wct}" var="w">
   <apex:column headerValue="AccountName" value="{!w.Location}"/>
      <apex:column headerValue="CustomObjectField1" value="{!w.mobilephone}"/>
         <apex:column headerValue="CustomObjectField2" value="{!w.Category}"/>
   </apex:pageblockTable>
  </apex:pageBlock>  
  </apex:form>  
 </apex:page>

public class SampleWrapperClassForThreeObjects
{
    public list<Testwrapperclass> wct{get;set;}
    public class Testwrapperclass
       {
           public string name1{get;set;}
           public string email{get;set;}
           public string mobilephone{get;set;}
           public string Location{get;set;}
           public string Category{get;set;}
       }
       
       public SampleWrapperClassForThreeObjects()
       {
           wct = new list<Testwrapperclass>();
       }
       public void displaydata()
       {
           list<Account> accList = [select id,name from Account limit 5];
           list<Contact> conList = [select id,email,mobilephone from Contact limit 5];
           list<Workshop__c> wrkList = [select id,Location__c,Category__c from Workshop__c limit 5];
           
           for(Account acc : accList)
             {
               for(integer i=0;i<conList.size();i++)
                 {
                   for(Integer j=0;j<wrkList.size();j++)
                     {
                       Testwrapperclass tt = new Testwrapperclass();
                       tt.email = conList [i].email;
                       tt.mobilephone = conList [i].mobilephone;
                       tt.Location= wrkList[j].Location__c;
                       tt.Category = wrkList[j].Category__c;
                       wct.add(tt);
                     }
                 }
             }
       }
}