The following code should do what you want. You could also add blinking animations, have look at this CursorDelegate example.
The only issue with SVG in QML is the poor aliasing. What you could do is compose the "pin" of two Rectangles one with rounded corners (radius property) and the other one rotated. Or you could have a look at how to get rid of aliasing with SVGs in QML.
Instead of using PathSVG you could also compose your pin icon of PathLine and PathArc.
Keep in mind that I didn't pay attention on dynamic placement of the pin and its scaling, I tweaked the values until it looked alright. Another thing would be to scale the pin in relation to your font size.

import QtQuick 2.0
import QtQuick.Controls 2.15
import QtQuick.Shapes 1.15
Item {
width: 640
height: 480
TextArea {
anchors.centerIn: parent
wrapMode: TextArea.Wrap
color: "gray"
font.pixelSize: 24
background: Rectangle{
implicitWidth: 300
implicitHeight: 200
radius: 3
color: "white"
border.width: 1
border.color: "black"
}
placeholderText: qsTr("Enter description")
cursorDelegate: Item {
width: 1
Rectangle {
id: rectangle
color: "black"
y: 1
width: 2
height: parent.height - 2
Shape {
x: -8
y: rectangle.height + 2
ShapePath {
fillColor: "red"
strokeWidth: -1
scale: Qt.size(0.2, 0.2)
PathSvg { path: "M 45,90 C 25.463,90 9.625,74.162 9.625,54.625 c 0,-8.722 3.171,-16.693 8.404,-22.861 L 45,0 71.97,31.765 c 5.233,6.167 8.404,14.139 8.404,22.861 C 80.375,74.162 64.537,90 45,90 Z" }
}
}
}
}
}
}