You can use the background-attachment: fixed property in css to achieve this. Take a look at this codepen: fixed bg while scrolling
Code Snippet:
@import url('https://fonts.googleapis.com/css?family=Quicksand');
html,
body {
height: 100%;
}
.wrapper {
height: 100%;
font-family: 'Quicksand', sans-serif;
line-height: 1.5;
word-spacing: 4px;
letter-spacing: 1px;
}
.fixed-bg {
background-attachment: fixed;
background-repeat: no-repeat;
background-size: cover;
background-position: center center;
height: 100%;
width: 100%;
color: white;
text-align: center;
display: table;
}
.fixed-bg h1 {
display: table-cell;
vertical-align: middle;
}
.scroll-bg {
background-color: #0f0f0a;
padding: 10px 70px;
color: #676767;
}
/* first section */
.bg-1 {
background-image: url('https://www.dl.dropboxusercontent.com/s/dk3s266jb5klmba/bg1.jpg');
}
/* third section */
.bg-2 {
background-image: url('https://www.dl.dropboxusercontent.com/s/jcord1lxh30e02z/bg2.jpg');
}
/* fifth section */
.bg-3 {
background-image: url('https://www.dl.dropboxusercontent.com/s/rsk15kp7azmsi27/bg3.jpg');
}
<div class="wrapper">
<!-- wrapper div starts -->
<div class="fixed-bg bg-1">
<h1>Fixed Background scrolling</h1>
</div>
<div class="scroll-bg">
<h3>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec in dolor tempor, posuere mi id, eleifend magna. Nulla at lectus magna. Etiam sodales arcu at lectus porttitor accumsan. Orci varius natoque penatibus et magnis dis parturient montes, nascetur
ridiculus mus. Curabitur id urna dolor. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Proin et pharetra justo, quis suscipit risus. Maecenas tincidunt efficitur ex in pharetra.</h3>
</div>
<div class="fixed-bg bg-2">
<h1>Fixed Background scrolling</h1>
</div>
<div class="scroll-bg">
<h3>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec in dolor tempor, posuere mi id, eleifend magna. Nulla at lectus magna.</h3>
</div>
<div class="fixed-bg bg-3">
<h1>Fixed Background scrolling</h1>
</div>
</div>
<!-- wrapper div ends-->
When it comes to how to implement it in elementor, you can use unlimited elements to create a custom widget and then place it on your elementor page.
I hope this helps in any way. Cheers!