CMakeLists.txt

# suppose you have created a ui file called configwin.ui
cmake_minimum_required (VERSION 2.6)

project(tst)

find_package(Qt5Widgets)

set(CMAKE_AUTOMOC ON)
set(CMAKE_INCLUDE_CURRENT_DIR ON)

QT5_WRAP_CPP(tst_hdr_moc configwin.h)
QT5_WRAP_UI(tst_form_hdr configwin.ui)

add_library(configwin ${tst_hdr_moc} ${tst_form_hdr})
qt5_use_modules(configwin Widgets)

add_executable(tst setting.cpp configwin)
qt5_use_modules(tst Core Gui Widgets)

configwin.cpp

#include "configwin.h"

ConfigWin::ConfigWin(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::ConfigWin)
{
    ui->setupUi(this);
}

ConfigWin::~ConfigWin()
{
    delete ui;
}

configwin.h

#ifndef CONFIGWIN_H
#define CONFIGWIN_H

#include "ui_configwin.h"

namespace Ui {
    class ConfigWin;
}

class ConfigWin : public QDialog
{
    Q_OBJECT

public:
    explicit ConfigWin(QWidget *parent = 0);
    ~ConfigWin();

private:
    Ui::ConfigWin *ui;
};

#endif // CONFIGWIN_H

setting.cpp

#include <QApplication>
#include "configwin.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    ConfigWin w;
    w.show();

    return a.exec();
}