procedure Form1_Button1_OnClick (Sender: TObject; var Cancel: boolean);
var
OpenDialog: TOpenDialog;
ArchiveFile: String;
zip:TZipFile;
begin
  zip:=TZipFile.Create;
  OpenDialog := TOpenDialog.Create(Form1);
  if OpenDialog.Execute then
     begin
        Form1.Edit1.Text:=OpenDialog.FileName;
        try
         zip.Open(OpenDialog.FileName,zmRead);
         for ArchiveFile in zip.FileNames do
          Form1.Memo1.Lines.Add(ArchiveFile);
         zip.Close;
         finally
        zip.Free;
       end;
     end;
end;

for ArchiveFile in zip.FileNames do